1. Field of the Invention
The present invention relates to a co-ordinates input device in which data is input by operating an operation region using input pens, fingers, or the like, and also relates to a method for producing such co-ordinates input devices.
2. Description of the Prior Art
FIG. 6 to FIG. 9 show a co-ordinates input device of the prior art in which an operation region is operated by input pens or the like.
FIG. 6 is a side view of the co-ordinates input device of the prior art, FIG. 7 is a plan view of a lower transparent substrate member of the prior art, FIG. 8 shows the back surface of an upper transparent substrate member of the prior art, and FIG. 9 is a cross-sectional view taken along the line IX--IX of FIG. 7.
In the co-ordinates input device of the prior art, the lower transparent substrate member 20 is composed of: a transparent glass substrate 21; an ITO film (a transparent resistive film made of indium oxide) 22 formed on the entire upper surface of the transparent substrate 21; electrodes 23 and 24 both made of silver, etc. and provided on the ITO film 22 in parallel with each other and at a given distance from each other; an operation region 25 formed between the electrodes 23 and 24; an insulating film 26 provided on the ITO film 22, outside the operation region 25 and along one side of the operation region 25; and lead electrodes 27 and 28, extending from one end of each of the electrodes 23 and 24, formed on the insulating film 26.
The upper transparent substrate member 30 is composed of: a transparent substrate 31 made of a synthetic resin such as transparent polyethylene terephthalate; an ITO film 32 formed on the entire lower surface of the transparent substrate 31; electrodes 33 and 34 both made of silver, etc. and provided on the ITO film 32 in parallel with each other and at a given distance from each other; an operation region 35 formed between the electrodes 33 and 34; an insulating film 36 provided on the ITO film 32, outside the operation region 35 and along one side of the operation region 35; another insulating film 37 which is provided on the ITO film 32, outside the operation region 35 and parallel to the electrode 34, and which connects to the insulating film 36; a lead electrode 38, extending from one end of the electrode 33, formed on the insulating films 36 and 37; and another lead electrode 39 extending from one side of the electrode 34 formed on the insulating film 37.
As is shown in FIG. 6, the upper transparent substrate member 30 and the lower transparent substrate member 20 oppose each other with insulating spacers 40 therebetween such that the ITO films 32 and 22 face each other and the parallel electrodes 33 and 34 oppose portions of the lower substrate on which the lower electrodes 23 and 24 are not formed.
In the above structure, the inputting of co-ordinates is carried out as follows: when the transparent substrate 31 is pressed using an input pen (not shown in the figures), it is deformed so that the upper and lower ITO films 32 and 22 are in contact. The ratio of the resistance between a contact point and the electrode 33 to the resistance between the contact point and the electrode 34 and the ratio of the resistance between the contact point and the electrode 23 to the resistance between the contact point and the electrode 24 are obtained via the lead electrodes 38, 39, 27 and 28.
The ends of the lead electrodes 27 and 28 of the electrodes 23 and 24 and those of the lead electrodes 38 and 39 of the electrodes 33 and 34 are formed close to each other to be connected to outside, for example, by connectors.
Therefore, the lead electrode 27 extending from the electrode 23 on the lower transparent substrate member 20 is formed on the insulating film 26 so as to be insulated from the ITO film 22 and the other lead electrode 28, and the lead electrode 38 extended from the electrode 33 on the upper transparent substrate member 30 is formed on the insulating films 36 and 37 so as to be insulated from the ITO film 32, the other electrode 34, and the lead electrode 39.
As is mentioned above, in the co-ordinates input device of the prior art, the insulating film 26 is formed for insulating the lead electrode 27 from the operation region 25 and the lead electrode 28, and the insulating films 36 and 37 are provided for insulating the lead electrode 38 from the operation region 35, electrode 34, and the lead electrode 39. Therefore, the production cost is raised due to the increased number of production steps and the material cost required for forming the insulating films 26, 36, and 37.
In addition, due to pin holes formed in the insulating films 26, 36, and 37, the lead electrodes 27 and 38 may have continuity with the ITO films 22 and 32, respectively, resulting in inferior products.
Furthermore, steps are formed between the ITO film 22 and the insulating film 26, and between the ITO film 32 and the insulating films 36 and 37. Therefore, when the lead electrodes are prepared by printing, they may be broken at the steps or may become very thin, also resulting in inferior products.